rejection vs exclusion

rejection and exclusion both are nouns.

Word	Noun	Adjective	Verb	Adverb
rejection	Yes	No	No	No
exclusion	Yes	No	No	No

As nouns, exclusion is a hyponym of rejection; that is, exclusion is a word with a more specific, narrower meaning than rejection:

rejection (noun)	exclusion (noun)
the act of rejecting something	the act of forcing out someone or something
the speech act of rejecting	a deliberate act of omission
(medicine) an immunological response that refuses to accept substances or organisms that are recognized as foreign	the state of being excluded
the state of being rejected	the state of being excommunicated